This application is a reissue of U.S. application Ser. No. 09/918,898 filed on Jul. 31, 2001, issued to U.S. Pat. No. 6,563,091. Other related applications are U.S. application Ser. No. 09/994,032, issued to U.S. Pat. No. 6,501,906, which is a CIP of U.S. application Ser. No. 09/918,898, and U.S. application Ser. No. 11/655,036 which is a continuation of this pending U.S. application Ser. No. 11/123,352.
The present invention relates to a device for evaporating volatile substances, in particular insecticides and/or aromatics.
Insecticide and aromatic evaporation devices are generally known. For example, evaporation devices are known where a small plate, introduced into an evaporation device and impregnated with an active ingredient, is heated in order to evaporate the active ingredient. Furthermore a method is also known by which a container containing a volatile substance is introduced into a housing of an evaporation device. This container comprises a wick that conveys the substance to be evaporated by means of capillary action out of the container, whereby the wick end protruding from the container is located next to a heating element such as a ceramic block. The substance is evaporated through the heat radiated by the ceramic block and can escape from the housing into the environment through aeration slits in the housing.
A disadvantage with prior evaporation devices is that it was not possible to adapt the degree of evaporation to the prevailing room conditions or to the different sensitivities of persons present in the room. Thus, for example, in smaller rooms with insufficient air ventilation, it is desirable to lower the degree of evaporation, which was not possible with prior evaporation devices. Furthermore, it is especially desirable to be able to adjust,the evaporation for insecticides, so that the degree of evaporation can be adjusted in accordance with the sensitivity of persons present in the room. This has also not been possible with the prior evaporation devices.
The ability to adjust the degree of evaporation for volatile substances is now known in the prior art. For example, EP 0 962 132 A1 discloses a device for the evaporation of volatile substances, in particular for insecticides and/or aromatics, by using a housing with a heating device located therein that comprises a ceramic heating block. The heating block uses a heating element to heat the heating block and evaporate a volatile substance. A container is carried in the housing and stores a volatile substance to be evaporated. A wick is inserted into the container with a wick end protruding from the container into a wick opening formed in the heating block. The invention discloses a switching device for activating and deactivating the heating element, as well as an adjusting device for adjusting the degree of evaporation. The housing of the evaporation device contains a large opening for receiving the container holder. On the outside of the container holder is a cylindrical extension with a helicoidal thread projection that extends in the form of spiral around the cylindrical extension. The thread projection interacts with a threaded bushing, already inside the housing, which has a receiving opening for the cylindrical extension of the container holder, and a corresponding counter-element to the thread projection on an inner side of this receiving opening. The bushing is moved by means of a pivoting lever to the outside of the housing. The container with a volatile substance to be evaporated is inserted into the container holder, with the wick extending into the wick opening in the form of a depression at the edge of the heating block above the container holder. To adjust the degree of evaporation, the bushing is rotated into a horizontal plane via the pivoting lever of the bushing. The interaction of counter-elements and thread projection make it possible for the container holder to be shifted in the longitudinal direction of the wick so that the wick end can be fixed in a different position relative to the heating block. This type of design, where the degree of evaporation is adjusted by changing the relative distance between the heating element and wick, is relatively expensive due to the number of complicated components required to effect the adjustments.
Another type of evaporation device is known from WO 98/19526, in which the heating output remains constant and the relative distance between the wick and the heating element is adjusted to control evaporation. The evaporation device comprises a housing into which a container with a wick can be screwed. The container is connected via a bushing to a swivel arm that moves in a guide slot, extending radially at an angle to the horizontal in the housing wall. Through the coupling of the swivel arm to the container, the container is lifted relative to the housing in the axial direction when the swivel arm is turned radially. As a result, the wick end protruding from the container may be shifted relative to the fixed heating element. On the whole, this is a relatively expensive and complicated construction with a great number of additional components, making the evaporation device expensive to manufacture.
It is also disclosed in EP 0 943 344 A1 that the relative distance between the heating element and wick can be changed to adjust the degree of evaporation while the heating output is maintained constant. The evaporation device includes a resistance heating element with a connecting plug that is threaded into a housing element where the container holding the substances to be evaporated is located. Pin openings are provided on the housing element into which locking pins are inserted in such manner that they mesh with the threads of the plug. The distance between the resistance-heating element and the wick end protruding from the container can be changed by twisting the plug element. The plug element can be mounted eccentrically in the housing element so that it too can be used to change the relative distance between the wick end and the resistance heating element to achieve the desired degree of evaporation. However, this method of adjusting the degree of evaporation is relatively complicated in construction and is also expensive to manufacture.
A similar design with the disadvantages discussed above is disclosed in WO 98/58692, wherein the tast of changing the evaporation capacity is accomplished by changing the position of the wick relative to the heating block.
Moreover, it is a common feature among all these known evaporation devices that they are relatively large in size and therefore less attractive aesthetically. The large size in design of the prior art is caused by the number of adjustment components needed to control the degree of evaporation. This large size turn affect the overall visual impressions of a room, and even an outdoor area.
The types of evaporation device disclosed above can only evaporate one substance at a time and requires a changing of the volatile substance container to evaporated different insecticides or aromatics. Especially when used for aromatherapy, it is often necessary to evaporate two or more aromatics together. This would normally require a corresponding number of evaporation devices, depending on the number of aromatics to be mixed and evaporated. As well, all these prior art devices would require the utilization of several evaporation devices to use multiple insecticides simultaneously.
It is therefore an object of the invention to provide a single evaporation device for multiple volatile substances, in particular insecticides and/or aromatics, which is simple in structure and can be produced economically yet the degree of evaporation can be easily adjusted to meet current requirements